Furnace



May 22, 1945. J. MCDONALD FURNACE Filed Sept. 18, 1942 Inventor 2 Sheets-Sheet 1 66 @ozza Zzf A ttorney FURNACE Fil 01 Sept. 18. 1942" J. MCDONALD Patented May 22, 1 945 FURNAGE James. McDonald, Dudley, England gas'signon of one-half to G. B. Electric Furnaces Limited,

Dudley, England; 7

Application September 18, 194.2;seria1 No. 458*,8269

In Great Britain October- 2, 1941 3. Claims. (01214 -18) This invention relates to the use of jigging, vibrating or reciprocating trays to carry work through continuous furnaces. The word furnace is used in a wide sense to include heat treatment chambers whether used for heating, cooling or maintaining temperature and the invention is designed to provide improved furnaces of the kind 1 to which the work is progressed on jigging vibrating or reciprocating trays.

From one important aspect the work carrying tray is carried upon transverse supports which extend through the side walls of the furnace, the ends of the supports being preferably carried in turn by external longitudinally extending meml bers suitably suspended or supported and trans-, 'm'itting r partaking of the movement of the tray.

Expansion and contraction of the tray caused by temperature changes can b allowed for by a slotted connection between tray and transverse support.

The above and other par-ts of the invention will be clearly understood from consideration of a typical furnace illustrated by the accompanying drawings, the parts for which a monopoly is desired being those set out in the claims. The particular form of furnace illustrated is intended to be capable of carrying out an annealing operation as a continuous process upon suitable small blanks or other articles.

In the digrammatic drawings- Fig. 1 is a side elevation showing the exterior of the furnace chamber, 7

Fig. 2 is a longitudinal sectional elevation of the same, showing also the feeding and discharge arrangements and the drive, and

.Fig. 3 shows the furnace chamber in cross-section.

As illustrated the furnace is of recuperative type in which the work is fed from a vibratin hopper I and chute 2 onto an upper tray 3 and then back along a return tray 4. The recuperative chamber is indicated at 5 and the heating chamber at 6 with heating elements indicated at I. The trays 3 and 4 are supported upon trans verse shafts 8, these shafts (except the end ones 80 which are secured to the trays) being a sliding fit in the grooves formed by brackets 9 secured under the trays. The grooves permit of expansion of the trays under heat. The shafts 8 and 8a project outside the furnace and are located in longitudinal beams l0 and II which act as connecting rods. The beams are in turn supported by inclined links l2, l3 respectively which guide the beams through a small upward and forward motion represented by the are through which the end of th inclined link is moved'by the action'of (for example) the eccentric and connecting rod l5. Alternatively the beams might be supported by inclined planes and rollers or other conventional and equivalent arrangements, and the links or other supports need not be of the same in number as the transverse shafts. When under heat, the relative position of the shafts 8 will not alter as they are located in the beams l0 and H which are outside the furnace and maintained in cold condition. The trays however, will expand longitudinally and remain in the dead level condition. On each-shaft end sealing means, for instance a large diameter brass cupped washer I6, is fitted, with a spring I! on the shaft end which maintains the constant pressure of the washer on the furnace casing. The cupped washer It can be heat insulated and is of such diameter that in any position of the stroke the enlarged hole in the furnace casing will be completely covered and therefore unnecessary heat losses or air infiltration will be eliminated, It will be appreciated that the possible arcuate movement of the beams I0 and l I and of the cross shafts 8 is so relatively slight, that the openings in the furnace through which the shafts extend may be and preferably are circular in cross section and of a diameter to permit the limited movement of the shafts.

In the case of the recuperative-furnace shown in which the work is progressed along an upper tray 3 and then back along a return tray 4, a convenient design is one in which the longitudinal beams I0 carrying the upper tray are suspended by links I2 from fixed pivots l8 above and the lower tray supported by links I 3 from fixed pivots l9 below. As shown, the connecting rods l5 are directly attached to the lower beams H and the upper beams l2 are coupled to the lower beams by connecting links 20. The upper links 12 will then incline downwards and forwards, so that upward movement along the arc and the working stroke of the upper tray are towards the right as shown by Figs. 1 and 2. And the lower links 13 will inolineupwards and backwards, so that upward movement along the arc and the working stroke of the lower tray are towards the left.

It will be noted that the trays 3 and 4 are shown of upwardly concave gradually curved form. It is found that this form enables articles of a great variety of shapes to be evenly progressed: and in particular in the manufacture of deep hollow cylindrical articles from sheets it providesla method of annealing blanks and cupped or cylindrical forms produced from the several stages of drawside walls, external members outside each side of the chamber, a, firm connection between the external members and the transverse members, one of the transverse members being firmly connected to the tray and longitudinally slotted connections for connecting the remaining transverse members to the tray, and means to impart jigging movement to the external members and thereby to the tray to progress the work along the tray.

2. In a furnace having side walls, upper and lower trays movable in said furnace, transverse members extending through the side walls and operatively connected to the trays for operating them, certain of the transverse members of each tray having a limited loose connection with the particular tray, upper and lower bars extendin longitudinally of each side wall and connected respectively to the ends of the extended ends of the transverse members of the upper and lower trays, links for supporting said bars for movement relative to the furnace, a connection between the upper and lower bars adjacent each side wall of the furnace, and means for directly operating the lower side bar beyond each side to thereby operate the upper bars and the trays. 3. A construction as defined in claim 2, wherein .the links supporting the upper and lower bars are relatively arranged to compel opposite feeding movements of the trays in operation of the bars.

JAMES MCDONALD. 

